SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d5d8d3e2148a178a29505763310698e155db9394661dc1dd1b7b2b73a418a70' 
  AND token = '82A4EzjsG2FlHaY4sbGvjJYyjoIV5jproBDbKNGtzIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}